Zephyr Dual Deploy Conversion

[JSW]

I decided to modify my L1 Cert rocket, Zephyr, to dual deploy so I can stuff some larger motors in it and maybe not lose it here in the northeast.

That's a great idea!

For my L2 I bought an Apogee Katana,... then realized it was basically a Zephyr with an e-bay kit. I should have just bought the e-bay kit and used it with the Zephyr I already had for my L1. So boring to (essentially) build the same rocket again. That said,... I think I need to extend the Katana by another body tube length. Go big or go home!

Thanks for the details re: how you built your e-bay with redundant electronics, shear pins, switches, etc. Good info. How did you size the deployment charges?

 

[TheTank]

That's a great idea!

For my L2 I bought an Apogee Katana,... then realized it was basically a Zephyr with an e-bay kit. I should have just bought the e-bay kit and used it with the Zephyr I already had for my L1. So boring to (essentially) build the same rocket again. That said,... I think I need to extend the Katana by another body tube length. Go big or go home!

Thanks for the details re: how you built your e-bay with redundant electronics, shear pins, switches, etc. Good info. How did you size the deployment charges?

I used a black powder calculator online then ground tested and adjusted slightly to get the primary right. For the backup, I took the primary and added .25g.

 

[MikeT]

Finished mine up and flew it yesterday. Perfect flight on a I180W to test. My charges need to be reduced a bit. I ground tested and backed them off a few grains. Looks like I can drop them a bit more. Perfect drogue deployment at apogee than the main at 600 ft. Landed 200 ft from the pad according to my Eggtimer GPS.

Mike

 

[ahmedcharles]

For my L2 I bought an Apogee Katana,... then realized it was basically a Zephyr with an e-bay kit.

Technically, the Peregrine is a Zephyr with an e-bay kit. The Katana is a Zephyr with an e-bay kit and a 54mm motor mount.

 

[Dan Griffing]

Technically, the Peregrine is a Zephyr with an e-bay kit. The Katana is a Zephyr with an e-bay kit and a 54mm motor mount.

https://www.google.com/search?q=bre...NC41LjWYAQCgAQGwAQ8&sclient=mobile-gws-wiz-hp
I modified my Peregrine with a 54mm motor mount and cladded it with carbon fiber. So it’s like a reinforced Katana.

 

[Dan Griffing]

 

[DMehalko]

Nice! Im going to put a wildman cone on my next zephyr for HED, set it up for 54mm also and fly it on a L1090. Wonder what the zepyhr altitude record is

 

[Dan Griffing]

Nice! Im going to put a wildman cone on my next zephyr for HED, set it up for 54mm also and fly it on a L1090. Wonder what the zepyhr altitude record is

You must be joking. An L1090 will tear the cardboard Zephyr apart. Its not capable of withstanding the transonic turbulence, the acceleration, or the stresses of supersonic flight.

I’ve seen many instances of cardboard rockets disintegrating at about 2,000 feet from a motor that’s too powerful for their construction.

Just because a big motor will fit doesn’t mean that its a wise idea to use it.

 

[techrat]

You must be joking. An L1090 will tear the cardboard Zephyr apart. Its not capable of withstanding the transonic turbulence, the acceleration, or the stresses of supersonic flight.

And yet so many people put giant motors into a Big Daddy kit. I assume there are ways to fortify the cardboard tube to withstand the stresses it will undergo. I mean, if you're going through the trouble to put a motor in your rocket that costs more than the rocket itself, maybe you can put at least one wrap of fiberglass on the tube and the fins.

 

[DMehalko]

You must be joking. An L1090 will tear the cardboard Zephyr apart. Its not capable of withstanding the transonic turbulence, the acceleration, or the stresses of supersonic flight.

I’ve seen many instances of cardboard rockets disintegrating at about 2,000 feet from a motor that’s too powerful for their construction.

Just because a big motor will fit doesn’t mean that its a wise idea to use it.

It would get some upgrades of course to support the power, 3 centering rings, glass sleeve, laminated fins, wildman cone and head end avbay. Ok project is on!

 

[cthunter01]

@DMehalko Dude, do it! I'll loan you an rf tracker transmitter if you need one. I'm not at my computer with openrocket to throw in my zephyr sim, but I imagine that would easily exceed 20k+ if it doesn't shred

 

[Dan Griffing]

It would get some upgrades of course to support the power, 3 centering rings, glass sleeve, laminated fins, wildman cone and head end avbay. Ok project is on!

Make sure that the fin filets are heavy enough and reinforced. The transonic turbulence on even 1/8” fiberglass fins can tear them off if the filets aren’t strong enough.

I even had to redo my Mad Cow SDX3 fin filets for the big motors when they started to show cracking with K motors.

And gradually increase the motor power while checking for damage to see if you need further reinforcements.

I’ve universally seen sad results when someone uses the biggest motor that will fit for a Level-2 certification attempt.

 

[SkyFire]

Put a 54mmt in mine. Didn't beef it up because I'm not using bigass motors!

 

[techrat]

I’ve universally seen sad results when someone uses the biggest motor that will fit for a Level-2 certification attempt.

I can't imagine what would cause someone to do that. You'd think that they would want to use the smallest motor that gets you the cert. Why do people try to shoot for the moon with a cardboard rocket? Is it because they really don't know any better or is there some macho thing going on where they want to hit an altitude record before they've even completed a cert?

 

[cthunter01]

Make sure that the fin filets are heavy enough and reinforced. The transonic turbulence on even 1/8” fiberglass fins can tear them off if the filets aren’t strong enough.

I even had to redo my Mad Cow SDX3 fin filets for the big motors when they started to show cracking with K motors.

And gradually increase the motor power while checking for damage to see if you need further reinforcements.

I’ve universally seen sad results when someone uses the biggest motor that will fit for a Level-2 certification attempt.

So you're saying don't go with an 'O' motor for my L3...

 

[Dan Griffing]

Im using two 2-56 shear pins to hold the cone secure during drogue ejection. The second ejection is strong enough to break/shear the pins and deploy the main when the time comes.

Cardboard isn’t as good at shearing the pins as fiberglass. Sometimes they only bend and tear the cardboard holes bigger.

 

[Dan Griffing]

So you're saying don't go with an 'O' motor for my L3...

I’m generally a cautious minimalist. Don’t increase the risk factors beyond what’s necessary for certification.

Of course I didn’t take my own advice for my own L-2 certification. I added dual deployment to my Zephyr hoping to demonstrate my expertise to the very senior rocketeers in my prefect because I was a retired engineer and it was only my second launch a month after my L1.

But I ground-tested the dual deployment BP ejections and chute packing about a dozen times before the launch and worked out a lot of problems.

 

[Dan Griffing]

I used a black powder calculator online then ground tested and adjusted slightly to get the primary right. For the backup, I took the primary and added .25g.

In addition, I would recommend multiple ground level dual deployment tests. You learn more from testing than simply doing calculations. There are so many factors that need to be tested.

I found the Eggtimer Proton dual deployment flight controller to be practically indispensable for doing ground testing.

 

[MikeT]

Cardboard isn’t as good at shearing the pins as fiberglass. Sometimes they only bend and tear the cardboard holes bigger.

Use brass disks to beef that up. Works Great. I'm using 3 -2/56 pins in mine cuts them clean.

https://www.rocketryforum.com/threads/shear-pin-shear-plates-in-your-cardboard-tubes.136706/
Mike

 

[Dan Griffing]

I can't imagine what would cause someone to do that. You'd think that they would want to use the smallest motor that gets you the cert. Why do people try to shoot for the moon with a cardboard rocket? Is it because they really don't know any better or is there some macho thing going on where they want to hit an altitude record before they've even completed a cert?

Probably both.

I saw it happen multiple times at LDRS-39. When the announcer described the rocket and motor, I said to myself “This isn’t going to end well.” — And it didn’t.

I saw the same thing happen at a local launch when someone tried to launch a Blue Tube rocket with a large L motor with spectacular results. The fins sheered right off just before the rocket turned sideways and came apart. They initially thought the motor might have CATOed, but a later examination showed that it was structural failure.

I think there’s a natural inclination to impress the other rocketeers at a launch. But reality is a harsh mistress and she extracts a high price for undeserved hubris.

 

[Dan Griffing]

Put a 54mmt in mine. Didn't beef it up because I'm not using bigass motors!View attachment 551311

I recognize those slotted fins! Its amazing how ubiquitous the Zephyr is. Did you notice the sound that those slotted fins make?

 

[SkyFire]

I recognize those slotted fins! Its amazing how ubiquitous the Zephyr is. Did you notice the sound that those slotted fins make?

No, I didn't notice any whistle with these fins.
I have an X-CELERATOR that definitely whistles.

 

[rocketman328]

I can't imagine what would cause someone to do that. You'd think that they would want to use the smallest motor that gets you the cert. Why do people try to shoot for the moon with a cardboard rocket? Is it because they really don't know any better or is there some macho thing going on where they want to hit an altitude record before they've even completed a cert?

I’ve been in this hobby since the 1980’s, I’ve noticed that many have more money than brains. Not always a lot of “ rocket science” going on.

 

[rocketman328]

Probably both.

I saw it happen multiple times at LDRS-39. When the announcer described the rocket and motor, I said to myself “This isn’t going to end well.” — And it didn’t.

I saw the same thing happen at a local launch when someone tried to launch a Blue Tube rocket with a large L motor with spectacular results. The fins sheered right off just before the rocket turned sideways and came apart. They initially thought the motor might have CATOed, but a later examination showed that it was structural failure.

I think there’s a natural inclination to impress the other rocketeers at a launch. But reality is a harsh mistress and she extracts a high price for undeserved hubris.

I think your comments are right on.